Method of treating ores.



UNITED STATEEiATENT orrion.

p, I i i inhycomem: H Beilt known thatl, James E. PQRTER, a citizen of the' United States,.res1dmg at Syracuse, inthe county of Onondaga and.

:State of Neiy' York, have invented certain 'new and -u'seful Improvements in Methods jof Treating Ores, of which the following is a specification; i

particularly the'precious metals, may be en 1 The object of this invention is the provision of a method whereby the values, and

Hfpeditiously, economically and efficiently rev redffrorn their ores. 1-

.; g-di f totheinvention the finely fl yided ore'or pulpis agitated in a solvent so I f lution," asacyanid solution, whereby the ya'lues"arm-dissolved; and these are then precipitated"'inlpifesence ofthe ore pulp in such formthatfthey may be at once wlthred, ayailable for further treat-- drawn or separated therefrom, and re ov- ,Ine'htfr I. f t l 'j'preferred embodimentof the 111- yention, the Values are precipitated by 2.5,, v,

means'ofplates of aluminum or aluminum ""alloysforotherforms of the metal presenting "extended. surfaces of aluminum from Y which the Values may readily be removed.

i In the recovery of gold and silver by the cyanidprocessit'has been customary to separate 'th'e metal-bearing solution from the ore, andto precipitate the values from the clear solut on by the actlon of zinc, alumr Ynum,"metallioalloys or mixtures, or by the action o'fa'n electric current. The separanon? of theisolution from the ores involves 'howey'ei' very considerable costs and expenditure of time, particularly When the ores are ifinelysubdivided or are treated in the tor-m of 'slimes: Ion the.v other hand, the values lare much more quickly and completely dissolved from ores, in a state of Very minute subdivision. According to the present invention I I am enabled to dissolve the ya l ues quicklyand with substantial completeness irom fine ores or slimes, andto recojyer such yalues n ava lable form Without the necessity of firstjseparatmg the solut on -from -vthepulp by filtration o1" sedimenta tion and without the use of mercury or other expensiveprocedure.

I preferto proceed substantially as followsg-The ore is ground in a ball mill or nch anew otherwise to.-,;extre1ne, fineness, preferably ;-,more W111 pass through a.

, lSr' i e -i j t lt 't t3" PatentedSept;5, 1911i lipplicaticnfileci January 17,1910, No. i v

ns E DWAnggoBppnn, or srnaousn, new some, ssre-nonmo rrrnausrr MINING EQKQJBZKQTIQBI 'ir'trgini, DEBOCHESQERQNEW Yeas, n oonronarrorr or NEW g mma or TREATINIF ones.

concentration of the alkali and the duration of treatment Will of course vary with the character of the ore, enough alkali be-.

ing usually added to insure that a proper proportion of protective alkali, say lgto 2 pounds per ton of solution, remains after the preliminary treatment. In the specific illustrative example of the treatment of the gold and silver bearing sulfid ores from the Tonopah district, it has been found that satisfactory results are secured by agitat ing the ore with a solutionc'ontaining approximately three ounces of commercial caustic soda for each 80 pounds of Water 51- a period of 1015 minutes, the weight of ore being about one-half that of the solution. The cyanid is then added and the agitation and aeration continued. For ores containing chiefly gold the cyanid solution may be highly dilute, as is Well understood, whereas for ores Which carry relatively large proportions of silver,-as those from the Tonopah district, a larger proportion ofcyanid up to 0.4: per cent. of the weight of the solution, or more, is required.

It is highly "important that the aeration of the mixture should be effective, and.

suspended therein for long periods, scouring the suspension of the fine ore, and main taining oxidizing conditions around each particle of the ore; Under such conditions sulfid ores are effectively treated in the raw state, the sulfur undergoing oxidation with.

formation of thiosulfates, as more fully pointed out in my copending application, Ser. No, '5.38,t02, filed January l7, 1910. By

this treatment the gold and silver are quickly brought into solution, and the 30011", mulation in the solution of inert or deleterione compounds, as the soluble sulfide or pelysnlfids, is avoided The ultimate 'reac' I tion products of tread-center such sulalkali fid ores with cyanid solutions, viz., the thiosulfates and hydroxids, are

7 themselves .efficient solvents for the values,

as pointed out in said application. Any copper present in the ores will also pass into solution. The temperature of the solution is preferably maintained at about 180- 190 F. as the solvent action is thereby greatly accelerated. j

i As soon as the solution has proceeded to a sufiicient extent, for example about one-half hour after the: introduction of the cyanid, plates of aluminum'or an aluminum alloy are mtroducedinto the suspended pulp or moved therethrough, whereby the values are precipitated and the combined cyanid regenerated. It is necessary merely to observe the precaution that the precipitate should not be permitted to accumulate on flake or scale off into the pulp, as this would thefplates to such thickness that it tends to render its re-solution necessary and unduly prolong the operation.' The plates are removed, either intermittently by hand. or intermittently :or continuously by any suitable mechanical device, as a belt, conveyor or the like, and the values are brushed or wiped ofl, afterfwhich the plates are returned to the pulp, this'operationcontinuing so long as values are deposited. When no more values are deposited on the plates the barren solution is separated from the pulp in so far as may of. the solution In such, case however the 45;

,are not attained, for the reason that during advantages inherent in the present method the solution of-the'values from the ore there is a progressive diminution of the content of active cyanid in the solution, due to the formation of the soluble double cyanids of gold and silver, the action of cyanicids, etc.,

which'must be compensated by the addition 'of suflicient cyanid to maintain the solvent power: that is to say; the employment of aluminum to precipitate the values does not in such case lessen the consumption of cyanid during the solution or the time required for" treatment. According to the present '(.).method hovvever the values are precipitated continuously or from time to time as the solution proceeds, and the solution is at the same time regenerated or restored, whereby its solvent power is substantially maintained; the solution proceeds rapidly and '5 relatively'small additions of cyamd are required, the additions being merely such as correspond to losses of :a mechanical character or those due to the so-called cyanicids. This regeneration of the solution by the action of aluminum may be assumed to proceed in accordance with the following equations:

The method may be practiced in apparatus of various types, that of U. S. Patent I No- 887,268, issued May 12, 1908, to J. E. Porter and A.-L. Clark, being well adapted for the purpose. The air which aerates the liquid'and maintains the fine ore or slimes suspended therein is in this case introduced through a porous. bedl underlying the solution in such manner that it slowly, gently,

uniformly and completely permeates and traverses the mass, without inducing therein such circulation as would abrade the precipitated values from the aluminum plates,

an effect which is further dependent upon the fineness of the ore, with the consequent readiness with which it may be suspended and. freedom from an abrading action. The

precipitate may be wiped from the alumi num plates after their removal with the greatest ease, but is nevertheless desposited on such plates and retained. thereby inthe midst of the body of suspended aerated and circulating pulp.

In treating ores containing copper the consumption of cyanid is normally high: but even in such case, the use of aluminum regenerates the solution by precipitation of the copper. solved and precipitated before the gold and silver, so that in certain cases at least it is practicable to separate the copper by precipitation on aluminum plates, and to utilize the regenerated solution for\ the recovery of the precious metals.

While the use of aluminum presents many advantages over that of zinc, particularly in.

respect to the regeneration or restoration of the solvent power "of the solution, and the ease of removal of the precipitated values, and while my invention contemplates primarily the use of aluminum or its alloys for effecting the precipitation, yet it may be advantageous under certain industrial conditions to employ other means of precipitation, as for example plates of zinc, a galvanic couple, or an electrolyzing circuit: and I do not therefore restrict-myself to the The copper 1s in large part' disemployment of aluminum vvhewthe ore, in a state of minute subdivision, is maintained suspended in the cyanid solution by the introduction thereinto of air in the form of minute bubbles, permeating and oxidizing the mass without establishing such circulation or a itation as to prevent the formation of an adlierent and recoverable film or precipitate of the values.

The word aluminum as employed in the claims is intended to include such alloys of aluminum as are effective for the precipitation of the values from cyanid solutions.

I claim:

1. The method of recovering precious metals from their ores, which consists in maintaining the fine o're suspended in a cyanid solution, and while so suspended separating the values from said solution upon surfaces of aluminum.

2. The method of recovering precious metals from their ores, which consists in maintaining the fine ore suspended in a heated cyanid solution, and While so suspended separating the values from said 90- lution upon surfaces of aluminum.

3. The method of recovering precious metals from their .ores, which consists in maintaining the line ore in suspension in a cyanid solution by the introduction thereinto of air in minute bubbles, and While so suspended separating the values from said solution.

4: The method of recovering precious metals from their ores, which consists in maintaining the fine ore in suspension in a cyanid solution by the introduction thereinto of air in minute bubbles, and while so suspended separating the values from said solution upon surfaces of aluminum.

5. The method of recovering precious metals from their ores, which consists vin subjecting the ores to the solvent action of a c anid solution, and regenerating said solution during the operation of dissolving the values, by means of aluminum.

In testimony whereof, I afiix my signature in presence of two witnesses.

JAMES EDWARD PORTER.

Witnesses:

E. E. CARPENTER, MICHAEL A. CAHILL. 

